The effects of mother-infant skin-to-skin contact (Kangaroo Care; KC) on autonomic functioning, state regulation, and neurobehavioural status was examined in 70 preterm infants, half of whom received KC over 24.31 days (SD 7.24) for a total of 29.76 hours (SD 12.86). Infants were matched for sex (19 males and 16 females in each group); birthweight (KC, 1229.95 g [SD 320.21]; controls, 1232.17 g [SD 322.15]); gestational age (GA) (KC, 30.28 weeks [SD 2.54]; controls, 30.19 weeks [SD 2.65]); medical risk; and family demographics. Vagal tone was calculated from 10 minutes of heart rate before KC and again at 37 weeks' GA. Infant state was observed in 10-second epochs during four consecutive hours before KC and again at 37 weeks' GA. Neurobehavioural status was assessed at 37 weeks' GA with the Neonatal Behavioral Assessment Scale (NBAS). Infants receiving KC showed a more rapid maturation of vagal tone between 32 and 37 weeks' GA (p=0.029). More rapid improvement in state organization was observed in KC infants, in terms of longer periods of quiet sleep (p=0.016) and alert wakefulness (p=0.013) and shorter periods of active sleep (p=0.023). Neurodevelopmental profile was more mature for KC infants, particularly habituation (p=0.032) and orientation (p=0.007). Results underscore the role of early skin-to-skin contact in the maturation of the autonomic and circadian systems in preterm infants.